A display device such as, for example, a smartphone or a tablet includes a touch panel (referred to as a touch sensor or a touch screen in some cases). The touch panel has electrodes for detecting contact or approach of an object. With such a touch panel, a user interface that enables an input operation with respect to an image displayed on a display device can be realized.
In recent years, a variety of forms of user interfaces have been proposed. For example, the specification of US Patent Application Publication No. 2010/0134423 discloses that a sensor is arranged on an edge of an apparatus so that the apparatus can determine whether the apparatus is in the left hand and/or the right hand of the user. Further, the specification of US Patent Application Publication No. 2013/0300697 discloses a bended display that enables operations with respect to a main area of a front surface of a portable device and a sub area of a side surface of the portable device.